Conventional camera modules (solid-state image sensing devices) for capturing images used in portable phones and the like are arranged such that a circuit board, a lens, and a lens holder are incorporated into a package. The circuit board includes a solid-state image sensor (CCD (charge-coupled device) or CMOS (complementary metal-oxide semiconductor) sensor IC (integrated circuits)), an infrared filter, and a terminal. The lens holder holds the lens.
It is important for these camera modules to satisfy the following two conditions: (a) an optical center of the image sensing surface of the solid-state image sensor corresponds to an optical center of the lens; and (b) the plane surface of the image sensing surface and the optical axis of the lens are orthogonal to each other.
Poor alignment precision of the lens with respect to the solid-state image sensor disables the satisfaction of these conditions. This causes problems such as images are out of focus, or images are recognized dark by the solid-state image sensor.
In response to this, the position of the lens is adjusted at the final stage of manufacture right before the camera module is shipped, so as to satisfy the conditions. The distance from the center of the lens to the image sensing surface of the solid-state image sensor (optical distance or focal length) is adjusted to the image forming length of the lens in this adjustment of lens position.
However, an optical adjustment step requires high-cost investment in plant and equipment, as well as manpower. In addition, optical adjustment requires considerable skill; plenty of work hours are also required.
Furthermore, the lens holder requires a specific arrangement for optical adjustment in order to perform optical adjustment. Therefore, it is difficult to downsize the conventional camera module structurally. In addition, mass production is difficult if the lens holder is constructed by mechanical components. Moreover, material costs and the like occupy a high proportion of production costs. Consequently, production costs increase.
Patent Document 1 discloses a camera module which can easily perform optional adjustment, as illustrated in FIG. 20. In this camera module, a lens 211 is held by a lens holder 201. The lens holder 201 has contact with a glass plate 226. The glass plate 226 is arranged on the top surface of a solid-state image sensor 224 in high precision. This lens holder 201 is adhered to a circuit board 221 with an adhesive 227. This arrangement enables the optical distance (focal length) and the image forming length of the lens to be of the same length. The optical distance is the distance between the lens 211 and the solid-state image sensor 224. Thus, an optical adjusting step is not required in this arrangement.
Patent Document 2 discloses a lens driving device as illustrated in FIG. 21. An object of the lens driving device in Patent Document 2 is to reduce the size and weight of the lens driving device, and to prevent undesirable radial movement, even if the lens is moved in a straight direction. The lens driving device in FIG. 21 is arranged such that lenses 311a and 311b are moved to a position where electromagnetic force and elastic force of springs 313a and 313b are proportionate. The lens driving device allows the adjustment by use of electromagnetic force, by applying electric current to coils 315a and 315b. 
Patent Document 1
    Japanese Unexamined Patent Publication, Tokukai, No. 2004-301938 (published on Oct. 28, 2004)Patent Document 2    Japanese Unexamined Patent Publication, Tokukai, No. 2003-295033 (published on Oct. 15, 2003)
However, in the conventional arrangement, it is difficult to make fine adjustments in the lens position, thus causing the problem of poor lens alignment precision.
More specifically, the arrangement of Patent Document 1 is of a single-vision. Therefore, a position of a lens 211 cannot be changed once the camera module is assembled.
The arrangement of Patent Document 2 moves the lens by moving the whole lens holder. This inevitably requires a magnet (not illustrated), the coils 315a and 315b and the like of large size. Consequently, the weight which needs to be driven together with the lenses 311a and 311b is heavy. As a result, the fine adjustment of the position of the lenses 311a and 311b becomes extremely difficult to perform. Furthermore, a response speed in adjusting the position of the lenses 311a and 311b is slow, and electricity consumption required to adjust the lens position also increases.